OSPF uses three major categories of internal operation to eventually build routes:
Neighbors: A relationship between two routers that connect to the same data link, created so that the neighboring routers have a means to exchange their LSDBs.
Database exchange: The process of sending LSAs to neighbors so that all routers learn the same LSAs.
Adding the best routes: The process of each router independently running SPF, on their local copy of the LSDB, calculating the best routes, and adding those to the IPv4 routing table.
The previous few pages already discussed the last two items in the list, ...